Since Joseph Losey filmed Figures in a Landscape, one of the novels on the first Booker shortlist in 1969, the Booker Prize has been the source of many films, including such big-scale productions as Spielberg's Schindler's List and Anthony Minghella's The English Patient. Now the Australian writer-director Fred Schepisi has adapted the fine, small-scale 1996 prize-winner Last Orders by Graham Swift, who acknowledges William Faulkner's experimental novel of 1930, As I Lay Dying, as his original inspiration.

The Faulkner book unfolds in brief chapters seen from different characters' point of view and centres on the death of a matriarch of a deeply dysfunctional Mississippi family who undertakes a 10-day journey to fulfil her wish to be buried in her home town. Swift's novel is more congenial than Faulkner's and, this being a British road movie, it takes less than a day as three friends and the dead man's son drive from south London to scatter his ashes in the sea from the end of Margate pier.

Schepisi has inevitably dropped Swift's succession of brief, first-person narrative and relied on flashbacks (often very brief) and even flashbacks-within-flashbacks as the characters revisit memorable incidents in their lives over 50 years. The result is always lucid. He also uses the wide screen to keep his whole cast in view and at times to show them in contemplative isolation.

The dead man is Jack Dodds (Michael Caine), who runs a family butcher's in Bermondsey and, though he'd always harboured the desire to be a doctor, he's dedicated to his shop, even to the point of going into debt to keep it running.

His closest friend is Ray (Bob Hoskins), a cheerful bachelor and retired insurance clerk who enjoys immense success backing horses. Ray scarcely comes up to Jack's shoulders, but in flashback we see them bonding for life in the trenches of the Western Desert and in Cairo brothels during the Second World War. The most aggressive chum is Lenny (David Hemmings), a failed prizefighter prevented from being a contender by drink and laziness and reduced to selling fruit and veg from a cart. The most reserved of the quartet is Vic (Tom Courtenay), a prim undertaker, deeply happy in his profession and always on duty.

The film begins with the friends gathering in the Coach and Horses, the Bermondsey pub where they've met nightly for more than 40 years. But they won't hear the landlord shout 'last orders' today because they have Jack's 'last orders' about his ashes.

Any possibility of sentimentality is undermined from the start by the arrival of Vic with the ashes, which he places on the bar. There is something solemn, deeply moving about formal burial, and we retain in our minds the body in the coffin. There is, however, something more than a little absurd, even comic, about the ashes stuffed into a small plastic urn after cremation. Is this undifferentiated dust all that's left of a life? Can we hold these remains of a friend or relative without making some kind of a joke, even one we qualify by adding that he or she would have appreciated the jest?

Jack's wife Amy (Helen Mirren) refuses to make the journey, mainly because this is the day she visits their brain-damaged daughter who's been in an institution for more than 50 years and whom Jack always refused to see. Instead they're accompanied by Jack's cocky fortysomething son, Vince (Ray Winstone), who's rejected the family calling to become a successful used-car salesman and he brings with him from his showroom a gleaming Mercedes to honour his father.

The journey to the Kent coast takes in a visit to the Royal Naval Memorial which makes Vic recall his rewarding work as a naval medical orderly in the war, and Canterbury cathedral, where they're all moved in different ways and made to feel an affinity with the nation's past.

In the countryside, there's an initially explosive sequence where Vince stops by a deserted field and insists on scattering a fistful of ash where Jack and Amy first met while hop-picking in the late 1930s. Finally, after a good deal of beer and whisky at various pubs, they get to chilly out-of-season Margate, where Jack had always meant to retire. There's a wonderful long-shot of the quartet seen from behind at the end of the pier and a mortifying view of the cold, unwelcoming sea, an image of that emptiness that lies beyond us all.

Last Orders has echoes of Kingsley Amis's The Old Devils and Wallace Markfield's To An Early Grave (filmed as Bye Bye Braverman), and occasionally veers close to what might be called 'Last of the Winter Beer'. But it has its own truths as a moving study of the pleasures and obligations of friendship, and of facing up to a death and going on. It's also about the end of a working-class generation who grew up during the Depression, served their country in the war, believed in honour, duty and patriotism, lived quietly and had a stoical attitude to life.

It's a world far removed from Albert Square and recent mockney gangster pictures. They took on the obligations of work and marriage, though they're closer to their friends at the Coach and Horses than to their wives. For this reason, a brief affair Amy has with the gentle, considerate Ray is among the most memorable experiences of both their lives.

Schepisi always handles actors sympathetically and here he has a perfect cast, most of whom can draw on their own and their parents' experiences. Without a touch of patronisation, they sink into their characters and never attempt to steal scenes from each other.

Sign up for the Guardian Today

Our editors' picks for the day's top news and commentary delivered to your inbox each morning.